| Field experiments were carried to study the effects of different nitrogen fertilizer sources and topping methods on the growth, development and quality of flue-cured tobacco, which were studied from the agronomic characteristics, carbon and nitrogen metabolism enzymes, appearance quality, physical characteristics, Chemical composition, aroma substances and economic characteristics. The conclusions were as follows:1. the research on the agronomic characteristicsThe largest leaf length and maximum leaf width increased with the advancing growth periods. The tobacco plants grew slowly in the early growth period when organic nitrogen and inorganic nitrogen were applied in the treatment (T5); with the releasing of fertility gradually accelerated, the all indicators were better than the treatment of inorganic nitrogen in the later growth period. The organic nitrogen promoted the advantages of tobacco clearly after topping, and the best treatments were T5t3 and T5t2 about tobacco plants in maturity.2.the key enzymes of the carbon and nitrogen metabolismNR activity decreased gradually with the development and maturation of tobacco leaves before top-dressing; NR activity inT5 treatment was the highest in all growth periods before topping, NR activity was the lowest in T4 treatment early period but significantly higher in the squaring period as the Cake fertility is released . NR activity in the treatment of organic nitrogen (T4 and T5) was higher than NR activity in the treatment of pure inorganic nitrogen when the plants were in maturity period, NR activity was highest in the treatment of T5t2, followed by in the treatment of T5t1.Before topping of the flue-cured tobacco, INV activity showed a trend of increasing first and then downward with the growth and development of tobacco, steadily rose from the beginning of early stage, decline rapidly after middle stage until the budding stage decreased at a lowest level. INV activity of T5 treatment was all higher than other treatments in several Growth periods. INV activity of T2 treatment was particularly highest in the Inorganic nitrogen treatments after top-dressing, it indicated that ammonium nitrate promoted more than a single nitrogen source for the photosynthesis of tobacco, the treatment of T5t3 has the highest INV activity followed by T5t2.Before the deal of topping , the trend of theα-amylase activities was: lowest in the early stage, increased with the peak leaves grew into the functional period, significantly increased to the highest level in the middle stage, then declined with the further growth of leaves.α-amylase activities in the treatment of organic fertilizer (T4 and T5) was lower than in the pure inorganic nitrogen treatment (T1, T2 and T3) when they were at early stage and middle stage but was higher in budding stage. Organic fertilizer was lower first then higher than inorganic fertilizer, Starch increased slowly first then fast with the growth of the tobacco plants. The different topping methods did not affectα-amylase activities, the trend is t1 <t2 <t3; each treatment the lowest of AM were in the T3t1, the highest activity is in T4t3, T5t2 activity is relatively high.3.Research on the quality of the appearanceAmmonium fertilizer with higher efficiency did not fit with the need of growth and development of tobacco. The later stage of tobacco did not have enough strength of fertilizer. The maturation stage tended to lead false mature, which had bad influence on the appearance quality of tobacco. Topping later would make the nutrition of leaves absorb by the reproduction part. Then the leaves was short of nutrition, cannot mature normally, and leaded to poor appearance quality. The combination using of organic fertilizer and inorganic fertilizer conformed the fertilizer regular pattern of growth and development of tobacco, and the growth of tobacco can not display shortage of fertilizer. With suitable time of topping (budding stage), the maturity of tobacco was good, and the appearance quality was the best. T5t2 and T5t1 had the best regulatory among all the treatment. 4.Research on the physical characteristics Application of organic manure and the normal method of topping can effectively promote the tobacco leaf length, width and thickness to increase.Organic fertilizer and inorganic fertilizer each half of the fertilization can increase the expansion power of tobacco, while topping on budding period helped to improve the expansion power of lower leaves. Application of pure organic fertilizer and topping on budding period improved the quality of tobacco leaf weight; application of organic fertilizer can effectively lower the filling value of tobacco, helped to improve the economic efficiency of cigarette manufacturing industrial enterprises. Application of pure organic fertilizer or organic fertilizer and inorganic fertilizer each half of the fertilizer can reduce the leaf stem ratio, improve the quality of tobacco.5. The study on Chemical composition in flue-cured tobaccoBased on the same nitrogen source, the contents of reducing sugar in upper leaves of topping on budding stage were higher than that of topping on full flowering stage, with normal topping, the contents of sugar of the middle leaves were in appropriate range. Under the condition of inorganic nitrogen source, contents of sugar in lower leaves tended to increase with topping time going by, and tended to induce under the condition of organic nitrogen source. Based on the same topping ,with the increasing of contents of organic nitrogen, sugar content increased Which showed topping at proper time and to increase organic nitrogen application which was helpful for increasing sugar content in flue-cured tobacco and improvement of the tast and improving smoking quality. For K content of flue-cured tobacco at same stall positions, application of organic nitrogen was higher than inorganic nitrogen; with topping time going by, K content tended to induce, but different levels hadn't significant correlation Which indicated organic nitrogen fertilizer was helpful for improving K content and flammability of upper leaves. Topping on squaring stage and full flowering stage were helpful for degradation of starch of flue-cured tobacco, increasing sugar content, improving smoking quality of upper leaves. With application of pure organic nitrogen, starch content of flue-cured tobacco was lower than other levels. Manure combined with chemical fertilizers was benefit to induce the content of Cl, improved K/Cl ratio and flammability.6. The study of Neutral Aroma ConstituentsThe study showed that manure combined with chemical fertilizers and normal topping had a proved effective on improving aroma component of middle leaves of flue-cured tobacco, organic fertilizers combined normal topping was benefit to aroma constituents of upper leaves. Allow for it's impossible to apply inorganic fertilizer entirely in actual production, so manure combined with chemical fertilizers and normal topping up to improve the content of aromatic matter and leave quality.7. The study of economic characteristicsT1, T2, T3 and T5 had significant difference among different tobacco correlation in every index. So was T4, Organic fertilizer was able to activate soil nutrient, maintain soil nutrient ,keep cation exchange capacity large, meanwhile sucking nutrient was easy to break down and can be absorbed by plants. Large of organic matter was helpful for microbes living and propagating, promoting nutrient from Invalid state changed into effective state, in order to improve rhizosphere nutrition of plant. In terms of yield and quality of tobacco, topping on budding stage was lower than normal topping and topping on full flowering stage. Therefore, to delay the top time is a good method to improve yield and quality of tobacco. In all, T5 and T2 both had large field and good quality. |
PDF Full Text Request